According to a conventional random access preamble structure for an extended cell radius the length of a preamble sequence part and cyclic prefix (CP) are maintained equal to the preamble sequence part and CP of a standard preamble structure for a normal cell radius, and only a guard time (GT) is extended so as to be suitable for the maximum round trip delay.
Since the conventional random access preamble structure cannot consider the maximum round trip delay according to the extended cell radius in regard to a CP length, when the round trip delay of a preamble is longer than the CP length, it is not easy to detect a preamble signal from a frequency domain.
FIG. 1 is a diagram illustrating a 1 ms standard random access preamble structure for a normal cell radius. The 1 ms standard ransom access preamble structure is formed of a CP 101, preamble sequence part 102, and a GT 103 that is the maximum round trip delay.
FIG. 2 is a diagram illustrating a conventional random access preamble structure for an extended cell radius. As shown in FIG. 2, a CP 201 and a preamble sequence part 202 are maintained equal to the CP 101 and the preamble duration 102 of the standard preamble structure of FIG. 1, and only a GT 203 is extended so as to be suitable for the maximum round trip delay according to the extended cell radius.